1. Field of the Invention
The present invention pertains to a patient interface device, and, in particular, to a patient interface device that includes a mask and a mounting member that is coupled to and freely rotatable relative to the mask and that provides a connection of a headgear assembly. The free rotation of the mounting member and its configuration enables various configurations of headgear assemblies to be used with the same patient interface device, thereby providing convenience, ease-of-use, ease-of-adjustment and improved comfort to the patient.
2. Description of the Related Art
It is well known to treat a medical disorder or to diagnose, treat or monitor the condition of the patient, using medical equipment. For example, a patient may be monitored and treated for various sleep disorders in a sleep lab, home, or in some other setting. An example of a type of sleep disorder is obstructive sleep apnea, which is characterized by a collapse of the upper airways during sleep. Another sleep disorder is central sleep apnea, which is characterized by the suspension of all respiratory movement. Obstructive sleep apnea and central sleep apnea may also be combined in a condition referred to as mixed apnea.
In order to diagnose and/or treat such medical disorders, various equipment and devices are required for successful diagnosis and a resulting prescribed treatment. Further, there are numerous situations where it is necessary or desirable to deliver a flow of breathing gas, non-invasively, to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheotomy tube in their trachea. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle or a monitored condition of the patient, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), congestive heart failure, stroke, Cheynes-Stokes respiration, etc. Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Patients suffering from a pulmonary or respiratory disorder, such as obstructive sleep apnea, are often treated with a pressure support device, such as a continuous positive airway pressure (CPAP) device. A CPAP device delivers a flow of fluid to the airway of the patient throughout the patient's breathing cycle in order to “splint” the airway, thereby preventing its collapse during sleep. In another type of treatment, bi-level positive pressure therapy is provided to the patient, in which the pressure of air delivered to the patient's airway varies or is synchronized with the patient's breathing cycle to maximize therapeutic effect and comfort to the patient. A pressure support device may also provide “bi-level” pressure support, in which a lower pressure is delivered to that patient during the patient's expiratory phase then during the inspiratory phase.
It is also known to provide an auto-titration positive pressure therapy in which the pressure provided to the patient changes based upon the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, or upper airway resistance. Such a device adjusts the pressure delivered to the patient, based on whether or not the patient is snoring. For example, a pressure support device may actively test the patient's airway to determine whether obstruction, complete or partial, could occur and adjust the pressure output to avoid this result.
Other modes of providing positive pressure support to a patient are known. For example, a proportional assist ventilation (PAV®) mode of pressure support provides a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing effort to increase the comfort of the patient. Proportional positive airway pressure (PPAP) devices deliver breathing gas to the patient based on the flow generated by the patient.
For purposes of the present invention, the phrase “pressure support system”, “pressure support device”, or “positive pressure support” includes any medical device or method that delivers a flow of breathing gas to the airway of a patient, including, but not limited to, a ventilator, CPAP, bi-level, PAV, PPAP, or bi-level pressure support system.
Because such patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP or other positive pressure therapy to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. One concern in such a situation is that the patient interface device is as comfortable as possible, otherwise the patient may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy.
In order to provide a flow of gas to a patient, the patient must use a patient interface device, such as a respiratory mask, as known in the art to communicate the flow of gas with their airway. These respiratory masks are provided in many variations, such as nasal masks, nasal and oral masks, mouth masks, full-face masks, etc. However, all of these mask devices are used to provide a breathing gas, such as oxygen, air or a combination thereof, to the patient.
Typically, the flow of gas is provided by a pressure generating device, such as those devices discussed above, and is communicated from the pressure generating device to the patient interface device via a flexible conduit, which is also known as a patient circuit. It is also known to deliver the flow of gas from an oxygen source, such as a pressurized oxygen tank via a pressure regulator and a hose, to the patient interface device.
Typically patient interface devices include a mask shell having a cushion or seal member attached to the shell that contacts the surface of the patient. The mask shell and cushion are held in place by a headgear assembly that wraps around the head of the patient and is secured to the patient interface device. The mask and headgear in combination with the patient interface device form a patient interface device. A typical headgear assembly includes a headgear having flexible, adjustable straps that extend from the mask (patient interface device) to attach the mask to the patient. Other techniques for attaching a patient interface device use a vice-like device that anchors at the front and back of the patient's head to support the mask on the user. See, e.g., U.S. Pat. No. 6,516,802. While such conventional interface devices are generally accepted, there remains a class of users that do not find these devices to be sufficiently comfortable, too bulky, or otherwise inadequate. Thus, alternative techniques for interfacing a pressure support system to the airway of a patient are desired.
Because patient interface devices are typically worn for an extended period of time, it is important that the headgear assembly maintain the patient interface device in a tight enough seal against a patient's face to minimize gas leakage at the seal/patient interface without discomfort. Adjustability of the mask and/or the headgear, together with increased patient comfort, is paramount as is the maintenance of the seal between the mask and the user's face. According to the prior art, various headgear have been developed that position the straps in various locations with respect to the mask in order to effect this seal.
An example of a conventional patient interface device that includes a collar and mask assembly that allow for the variable positioning of headgear straps is described in U.S. Pat. No. 6,412,488 to Barnett et al. (“the '488 patent”). As best seen in FIGS. 4A and 4B of the '488 patent, in order to prevent rotational movement of the seal member relative to the collar, a mounting member on the collar includes multiple protrusions, and the neck portion of the seal includes matching channels for receiving these protrusions. Accordingly, when the seal member is attached to the collar, the protrusions and channels prevent the collar from rotating relative to the seal member. In addition, the protrusions and channels are arranged such that only proper alignment of the seal member relative to the collar is allowed. In one embodiment, a conduit coupling member, which couples the mask to the patient circuit, is rotatable about the collar. This allows for movement of the patient with respect to the patient circuit. However, the device of the '488 patent, while moveable between various positions, is not fully flexible or rotatable with respect to the mask to which it is attached.
Another collar device for attachment to a mask, and to allow variable positioning, is disclosed in U.S. Pat. No. 5,662,101 to Ogden et al. (“the '101 patent”) The device taught by the '101 patent includes a rigid plate connected to a facial mask assembly by connecting detents on the plate to channels on the mask assembly. Straps are inserted through openings on the rigid plate in order to secure the mask assembly in a sealed position against the user's face. Multiple openings are available, such that a variety of strapping positions can be obtained. However, the assembly of the '101 patent is not rotatable with respect to the mask to which it is attached. A similar unrotatable plate or collar arrangement is illustrated in U.S. Design Pat. No. Des. 412,745 to Scheu.
Yet another conventional patient interface device that includes a collar is shown and described in U.S. Pat. No. 6,631,718 to Lovell (“the '718 patent”), which embodies a similar design and operation to the device taught by the '488 patent device. In particular, the Lovell device includes a retainer that is attachable to the shell of the mask. This retainer includes lower connection points and at least one upper connection point, as best illustrated in FIGS. 1, 2A, 7 and 9-11 of the '718 patent. While, like the device of the '488 patent, the assembly of the '718 patent permits multiple attachment points for variations in strap connection and positioning, the retainer is not rotatable about the shell of the mask. Instead, the retainer is positioned in a fixed position using tabs on the inlet of the mask and associated and mating slots on the retainer. Accordingly, while providing some variability in headgear or strap connection, the device disclosed in the '718 patent does not provide flexibility in attaching the headgear to the mask. A similar non-rotatable and inflexible headgear/strap assembly is disclosed in U.S. Pat. No. 6,823,869 to Raje et al., such as in, e.g., FIGS. A11 and F36.